The jack bean lectin, Concanavalin A (Con A), binds saccharides containing glucose or mannose residues in a manner analogous to an antigen-antibody reaction. The lectin precipitates glycoproteins containing the appropriate sugar residues and selectively agglutinates tumor cells. Although Con A is widely used as a probe to reveal alteration in the composition and organization of tumor cell membranes, the molecular properties of the agglutinin that are responsible for its binding of agglutinating activities are not completely understood. In order to provide insights into possible modes of interaction of the lectin with carbohydrate determinants of normal and transformed cells, it is necessary to understand the mechanism of binding of simple saccharides to the lectin and to determine the molecular properties of the protein associated with its carbohydrate binding specificity. We have previously used nuclear magnetic resonance (nmr) techniques to obtain information on the molecular interactions between saccharides and Con A as well as the functions of metal ion binding to the protein. The objectives of this proposal are to extend our previous studies using similar nmr techniques to: 1) investigate the mechanism of binding of saccharides to Con A, and 2) investigate the relationship between the metal ion binding properties of Con A and its saccharide binding activity.